type A1 ={
   readonly T1:number
}
type B1 ={
    T2:String 
}

type C1 ={
    T3:number,
    // T2:Boolean // 交叉类型会把相同成员的类型进行交叉
}& A1 & B1

let u:C1={
    T1:12,
    T2:"ghgh",
    T3:12
}
// readonly 只读修饰符
// u.T1 = 12;